Energy efficiency is the "low hanging fruit" of climate action. Energy efficiency covers a broad range of issues across all sectors of the economy. Overall costs of energy efficiency are generally low compared to other options. And many measures have low or negative net costs and short payback time.

Vending machines becoming more climate friendly. Photo credit: Coca-Cola

Here's an example from the business world that has been celebrated by the UNFCCC secretariat's Momentum for Change Initiative. The Coca-Cola Company committed to dramatically reduce its carbon footprint by cutting energy consumption 40% by 2010, and will replace all of its vending machines that use hydrofluorocarbons with more environmentally friendly refrigerants by 2015.

Numerous examples of energy efficiency have already been discussed by the ADP, the negotiation stream tasked with designing an effective global climate change agreement in 2015 and ramping up immediate climate ambition.

According the UN Environment Programme's Emissions Gap Report 2012, the total mitigation potential in 2020 for buildings alone is within range of 1.4-2.9 Gigatonnes C02 equivalent. And the International Energy Agency pdf-icon says that by unlocking cost-effective energy efficiency options, cumulative global economic output would increase by USD 18 trillion by 2035. The greatest financial gains would be in India, China and Europe. But other parts of the world can benefit, too.

For example, in Ghana the implementation of minimum energy performance standards for air conditioners is expected to reduce emissions by around 2.8 C02 Megatonnes equivalent over 30 years and save consumers around USD 64 million annually in energy bills. And in Nepal, a CDM project helps reduce fuel consumption by introducing fuel efficient cooking stoves. Apart from reducing deforestation rates and GHG emissions, the project also improves the living conditions of the poor families through reduced indoor air pollution.

Photo credit: Centre for Rural Technology, Nepal

It's important to keep in mind that the introduction of innovative policies that put a price on carbon, such as emissions trading and carbon taxes are a major driver of energy efficiency. China has implemented several pilot projects and approaches to explore carbon market opportunities, with a view to implementing national carbon trading.

European Union plans to improve efficiency of new cars (95 g/km – 40% improvement compared to 2007) and vans (147 g/km – 28% improvement compared to 2007) from 2020 can result in saving users of such vehicles on average EUR 3-4 thousand in fuel costs over the lifetime of each such vehicle.

There are numerous co-benefits to taking climate action with the help of energy efficiency, not least through health benefits from the reduction of water and air pollution. For example, measures in Mexico to reduce air pollution through improved brick kiln designs have already boosted fuel efficiency by 50% and reduced particulate pollution from kilns by 80%.

Efficient lighting cleanly meets growing demand. Photo by en.lighten

Another great example of efficiency highlighted by the UN Climate Change Secretariat's Momentum for Change Initiative is en.lighten, which is accelerating the transition to energy efficient lighting in developing countries where electrical demand is expected to grow rapidly. More than 130 countries still market inefficient incandescent lamps, and en.lighten aims to help these countries switch to more efficient lighting by 2016.